MI Polygon reshaping

[Milo Simonic]

A table consists of about 70 polygons (non-overlapping). I need to reshape certain mutual boundaries. I digitized the desired shape and using snap mode and reshape function I reshaped a boundary. Reshaping however only applies to one selected polygon. The neighbouring polygon maintains its unreshaped boundary. How to change/reshape a MUTUAL boundary of two polygons at the same time?   Milo